Front brakes sticking on

[TimJ 10]

Can anyone help diagnose my faulty brakes... not had the car long and it has been a nightmare.

 

My front brakes are sticking on to the point where the brakes smoke and I can hardly drive it anywhere. The symptoms can be more severe at some times than others; on occasions I can get a few miles no problem then sometimes the pedal firms up and then I know its going to get sticky.

 

I replaced both front callipers and switched from braided hoses to rubber ones with no difference.

 

I took it to a local garage who didn't know what the problem was, I then took it to a specialist who pressure bled the system, checked ABS valves (all OK) and checked the calliper pistons. They too did not know what the problem was but suggested it could be a faulty ABS unit.

 

Any ideas?

[TimJ 10]

Anyone help on this??

[DriverVR6 11]

By the sounds of it I would take a look at the servo as it may be getting stuck and not releasing it's pressure. I don't think it has anything to do with the ABS. Never a good idea to simply change stuff as most of what you change will be not the cause of the fault.

[24V Renshaw 0]

It won't be the servo itself, it will be the master cylinder jamming and not relieving the pressure.

This is a spring return piston and if it is sticking it will retain the pressure in the system.

 

Jay

[Roger Blassberg 0]

All the brakes would be binding if the master cylinder were sticking. I would be inclined to take the front calipers off their carriers and make sure that the slider pins are not sticking as a first approach. Then take the pads out and clean the backplates and the caliper carrier where the pads sit, and apply a touch of copper grease (not to the friction surfaces, obviously!!) to ensure that the pads are moving freely.

 

It is not unknown for flexible hoses to collapse inside and to hold some pressure after the brake pedal has been released, so new hoses may be required.

 

Best wishes

 

RB

[24V Renshaw 0]

Not necessarily. The rear bias valve might be taking enough pressure off that the rears are allowed to spring return enough to release. The front however still gets full pressure and wont return.

 

The original post stated he has replaced the calipers and the hoses on the front.

 

Have you tried disconnecting the ABS at all as it could be a stuck solenoid in there?

 

Jay

Edited June 1, 2012 by 24V Renshaw

[Roger Blassberg 0]

Must pay more attention.

Must pay more attention.

Must,,,,,,,,,

 

RB

[TimJ 10]

Thanks for the replies

Not tried disconnecting the ABS (there were no fault codes) should I just pull off the multiplug at the front of the unit?

 

I thought master cylinder next but, as DriverVR6 says, not good to replace any more parts than I have done so already when not sure of the cause...

 

What is supply like on master cylinders? I searched the forum quite a bit before posting this and people seem to be talking about difficulty getting them?